Frequently Asked Questions (FAQ)

Below are some frequently asked questions in three areas, with associated answers.

OpenModelica General

  • Q: OpenModelica does not read the MODELICAPATH environment variable,

    even though this is part of the Modelica Language Specification.

  • A: Use the OPENMODELICALIBRARY environment variable instead. We have

    temporarily switched to this variable, in order not to interfere with other Modelica tools which might be installed on the same system. In the future, we might switch to a solution with a settings file, that also allows the user to turn on the MODELICAPATH functionality if desired.

  • Q: How do I enter multi-line models into OMShell since it evaluates

    when typing the Enter/Return key?

  • A: There are basically three methods: 1) load the model from a file

    using the pull-down menu or the loadModel command. 2) Enter the model/function as one (possibly long) line. 3) Type in the model in another editor, where using multiple lines is no problem, and copy/paste the model into OMShell as one operation, then push Enter. Another option is to use OMNotebook instead to enter and evaluate models.


  • Q: OMNotebook hangs, what to do?

  • A: It is probably waiting for the omc.exe (compiler) process. (Under

    windows): Kill the processes omc.exe, g++.exe (C-compiler), as.exe (assembler), if present. If OMNotebook then asks whether to restart OMC, answer yes. If not, kill the process OMNotebook.exe and restart manually.

  • Q: After a previous session, when starting OMNotebook again, I get a

    strange message.

  • A: You probably quit the previous OpenModelica session in the wrong

    way, which left the process omc.exe running. Kill that process, and try starting OMNotebook again.

  • Q: I copy and paste a graphic figure from Word or some other

    application into OMNotebook, but the graphic does not appear. What is wrong?

  • A: OMNotebook supports the graphic picture formats supported by Qt 4,

    including the .png, .bmp (bitmap) formats, but not for example the gif format. Try to convert your picture into one of the supported formats, (e.g. in Word, first do paste as bitmap format), and then copy the converted version into a text cell in OMNotebook.

  • Q: I select a cell, copy it (e.g. Ctrl-C), and try to paste it at

    another place in the notebook. However, this does not work. Instead some other text that I earlier put on the clipboard is pasted into the nearest text cell.

  • A: The problem is wrong choice of cursor mode, which can be text

    insertion or cell insertion. If you click inside a cell, the cursor become vertical, and OMNotebook expects you to paste text inside the cell. To paste a cell, you must be in cell insertion mode, i.e., click between two cells (or after a cell), you will get a vertical line. Place the cursor carefully on that vertical line until you see a small horizontal cursor. Then you should past the cell.

  • Q: I am trying to click in cells to place the vertical character

    cursor, but it does not seem to react.

  • A: This seems to be a Qt feature. You have probably made a selection

    (e.g. for copying) in the output section of an evaluation cell. This seems to block cursor position. Click again in the output section to disable the selection. After that it will work normally.

  • Q: I have copied a text cell and start writing at the beginning of

    the cell. Strangely enough, the font becomes much smaller than it should be.

  • A: This seems to be a Qt feature. Keep some of the old text and start

    writing the new stuff inside the text, i.e., at least one character position to the right. Afterwards, delete the old text at the beginning of the cell.

OMDev - OpenModelica Development Environment

  • Q: I get problems compiling and linking some files when using OMDev

    with the MINGW (Gnu) C compiler under Windows.

  • A: You probably have some Logitech software installed. There is a

    known bug/incompatibility in Logitech products. For example, if lvprcsrv.exe is running, kill it and/or prevent it to start again at reboot; it does not do anything really useful, not needed for operation of web cameras or mice.